Load compensated series type flasher



P 1963 I -H. G.SIIBERG 3,403,294

LOAD COMPENSATED SERIES TYPE FLASHER Filed Sept. 14, 1965 I J 0 40 i INVENTOR 3,403,294 LOAD COMPENSATED SERIES TYPE FLASHER Hemming G. Siiberg, Union, NJ., assignor, by mesne assignments, to Wagner Electric Corporation, South Bend, Ind., a corporation of Delaware Filed Sept. 14, 1965, Ser. No. 487,242 4 Claims. (Cl. 315-409) ABSTRACT OF THE DISCLOSURE A series type flasher is compensated to flash greater and lesser loads at substantially the same rate. In one embodiment an auxiliary heater winding is energized to augment heating of the flasher pull ribbon whenever the lower load is flashed, thereby avoiding a change in flashing rate due to lower current flow when the flasher is switched from the greater to the lesser load. In another embodiment, a portion of the flasher pull ribbon is shortcircuited whenever the greater load is flashed, thereby avoiding a change in flashing rate due to higher current flow when the flasher is switched from the lesser to the greater load.

The present invention relates to a three terminal series type flasher which is suitable for use in either dual intensity or emergency automotive flashing circuits.

Series type flashers are now in wide use in the automobile industry. They are generally comprised of a buckling member which is deformed along one axis and held by an expansi'ble pull ribbon in a constrained position against the bias introduced by the deformation. When current is passed through the flasher, the pull ribbon expands and permits the buckling member to snap toward its biased position, opening the circuit of the signal lamps and causing the pull ribbon to cool and contract, thereby snapping the buckling member back to circuit closing position.

In the usual series type flasher, the on time depends upon the rate of heating of the pull ribbon whereas the off time is constant. Thus, when the lamp load is increased, the current through the flasher increases, shortening the on period of each cycle and correspondingly increasing the flashing rate. Automobile manufacturers require that the flashing rate and ratio, that is, the ratio of on time to the time of a complete cycle, be maintained substantially constant with change in lamp load. In dual intensity systems, where a higher lamp load is employed in the daytime than in the nighttime, the automobile manufacturers specifications cannot be met by the usual series type flasher. For the same reasons, the usual series type flasher cannot be used for emergency signalling wherein the lamp load is doubled.

In accordance with the invention, a series type flasher is provided with means for maintaining constant the heating rate of the pull ribbon at two different lamp loads and thereby maintaining constant both the ratio and rate of flashing.

Constant rate of heating of the pull ribbon at the two different loads is obtained in one embodiment of the invention by adding externally generated heat to the pull ribbon when the load is low and the flasher has been adjusted for standard operation at the higher load. The externally generated heat is provided by a heater coil, positioned in heat conductive relation to part or all of the pull ribbon which is energized during the on period of the flasher when the load is low, thereby augmenting the heat in the pull ribbon.

In another embodiment of the invention, the constant heating rate is obtained by reducing the heat generated in the ribbon when the load is high and the flasher has been adjusted for standard operation at the lower load.

United States Patent 3,403,294 Patented Sept. 24, 1968 The heat generated in the ribbon is reduced by shunting a part of the pull ribbon from the load circuit at the higher load to thereby reduce the effective resistance of the pull ribbon and consequently the heat generated therein by the load current.

For a better understanding of the invention and specific embodiments thereof, reference may be had to the accompanying drawings of which FIG. 1 is a diagrammatic representation of a flasher embodying the invention and in which means are provided for augmenting the heat generated in the pull ribbon at low lamp load;

FIG. 2 is a similar diagram of a flasher embodying the invention in which means are provided for effectively shunting a portion of the pull ribbon at higher lamp load;

FIG. 3 is a circuit diagram of a dual intensity circuit incorporating the flasher of FIG. 1; and

FIG. 4 is a similar diagrammatic circuit incorporating the flasher of FIG. 2.

The flasher of FIG. 1 includes a base 2 of insulating material through which extend three terminals 4, 6 and 8 for connection to an external circuit. Above the base 2 is a vane 10' which is fixedly secured to a support 12 which preferably comprises an extension of terminal 6. The vane is mounted as by welding on the upper end of the support 12 adjacent the lower central area of the vane. The vane 10 is bent or deformed about the longitudinal axis indicated at 14 so as to be normally convex toward the viewer. A pull ribbon 16 is secured under tension at its ends to diagonally opposite corners of the vane 10, these corners being turned toward the opposite surface of the vane to provide anchorage for the pull ribbon. A contact 18 is mounted on the pull ribbon 16 and a fixed contact 20, aligned with the contact 18, is mounted on a post 22 forming an extension of terminal 4. A heater winding 24 having an insulated coating thereon is wound about the pull ribbon 16 and has one end electrically connected to the pull ribbon. The other end of the winding 24 is connected to a post 26 comprising a continuation of terminal 8.

With the above described flasher, when a source of potential is connected to terminal 4 and a lamp load connected to terminal 6, with terminal 8 out of the circuit, the flasher will operate like prior art series type flashers in that when the circuit is closed, the current will flow from terminal 4 through contacts 18 and 20, through the pull ribbon to the blade and from thence to terminal 6 and the lamp load. Expansion of the pull ribbon, under the heat generated by the current therethrough, permits the vane to snap to contact open position. The pull ribbon then cools and contracts and snaps the vane to contact closing position. The cycle then repeats. The flasher, as above described and with terminal 8 out of the circuit, is adjusted for the desired rate and ratio for a given high load. When the load is changed to a lower load, terminal 8 is connected to ground so that current will flow not only from terminal 4 to terminal 6 when the contacts are closed but will also flow from terminal 4 through the turns of winding 24 to ground, that is, to the negative terminal of the source. Thus, current through the heater winding 24 will augment the heat generated in the pull ribbon 16 by the reduced load current and therefore by proper selection of the heater winding the flashing rate and ratio can be maintained constant at the two separate loads.

In FIG. 3 the flasher of FIG. 1 is shown connected in a dual intensity circuit with terminal 4 connected to the positive terminal of a battery 28, with terminal 8 connectable through a switch 30 to ground and with terminal 6 connected to the directional signalling switch 32 of the automobile circuit. Swith 32 may be, and preferably is, the Bell switch.

One fixed terminal of the Bell switch 32 is connected through a lamp load 34 to ground and through a second lamp load 36 and a switch 38 to ground. Lamp load 34 may represent the front and rear and pilot lamps on one side of the vehicle and the load 36 may represent either additional lamps on the same side of the vehicle or separate filaments of the lamps of load 34. The other fixed terminal of the switch 32 is similarly connected through a lamp load 40 to ground and through a second lamp load 42 and a switch 44 to ground. Lamp load 40 may be the signal lamps on the other side of the vehicle and lamp load 42 additional signal lamps or filaments in the lamp load 40 on that other side of the vehicle.

The flasher is adjusted as heretofore described in connection with the description of FIG. 1 for normal operation at high lamp load, that is, when switches 38 and 44 are closed and switch 30 is open. This corresponds to daytime driving. If, now, the additional lamps or filaments 36 or 42 are taken out of the circuit under nighttime conditions by opening switches 38 and 44 and switch 30 is closed, the heater winding 24 is energized to augument the heat generated in the pull ribbon by the reduced current flowing to the lamp load. In a physical embodiment of the circuit diagrammatically shown in FIG. 3, switches 30, 38 and 44 would be ganged together so as to be simultaneously operated, switch 30 opening when switches 38 and 44 close and vice versa. The ganging together of these switches is indicated by the dashed line 46.

Although the diagram of FIG. 3 has been described in connection with dual intensity systems, obviously the flasher could be similarly employed where the lamp load is doubled for emergency signalling.

In the embodiment of FIG. 2 wherein the flasher is adjusted for low load, the heater is dispensed with and two contacts 48 and 50 are mounted on the pull ribbon 16 and located in alignment with fixed contacts mounted on posts 22A and 26A, post 26A being a continuation of terminal 8A. As indicated 'by the diagram of FIG. 4, when the flasher of FIG. 2- is included in a circuit of the type of FIG. 3, terminal 8A is connected through a switch 30A to the positive terminal of the battery 28 and switch 30A is ganged with switches 38 and 44 to be closed when those switches are closed as indicated by the dashed line 52 in FIG. 4. The operation of this circuit is as follows:

With the flasher adjusted for operation at the low lamp load, that is, when lamps 34 and 40 only are in the circuit and switches 38 and 44 and 30A are open, the standard rate of flashing will be maintained during nighttime conditions. During daytime conditions, when switches 30A, 38 and 44 are closed, substantially no current will flow during the on period through the pull ribbon between contacts 48 and 50 "because these two contacts will be at substantially the same potential, each being connected through their mating fixed contacts to the source. Thus, the effective length of the pull ribbon is decreased during daytime conditions with a reduction in the heat which would be generated at the high load. Consequently, by proper spacing of the contacts 48 and 50, substantially constant rate and ratio is obtained. As in the circuit of FIG. 3, emergency rather than dual intensity flashing of the lamps could be controlled by the flasher.

The invention has now been described with reference to two embodiments thereof in each of which constant rate of heating of the pull ribbon is maintained at two diflerent loads. The constructional features of the flasher, aside from the elements which ensure the constant rate of heating, comprise no part of the present invention. For example, the shape of the vane, the orientation of the pull ribbon with reference to the deformation or the type of deformation therein could be varied within the scope of the invention so long as the flasher inself under one lamp load operates like a standard series type flasher. Flashers with various configurations of vane and of orientation of pull ribbon are well known in the art. Although in FIG. 1 the heater winding has been shown as encircling about half of the pull ribbon, more or less of the pull ribbon could be in heat conductive relation with the winding and the winding need not encircle the pull ribbon as it could be placed in close proximity thereto to be in heat conductive relation therewith. Other modifications within the scope of the invention will be apparent to those skilled in the art.

I claim:

1. A snap action flasher for flashing lesser and greater loads at substantially the same rate which comprises:

(a) a first terminal,

(b) a buckling member which is inherently biased toward a first position and held in a second position against said bias by a cold heat-expansible linear pull means secured to said buckling member under tension, said pull means expanding when heated to permit said buckling member to snap toward said first position, and said pull means-buckling member assembly being electrically connected to said first terminal,

(c) a movable contact mounted upon said pull meansbuckling member assembly,

(d) a second terminal,

(e) a stationary contact mounted upon said second terminal in position for cooperative make-and-break electrical connection with said movable contact, said first terminal, pull means-buckling member assembly, movable and stationary contacts and second terminal being arranged in series for current flow through all of said elements when said movable and stationary contacts are closed,

(f) a third terminal,

(g) a heater winding one end of which is electrically connected to said pull means and the other end of which is electrically connected to said third terminal, said heater winding being positioned in heat conductive relation to said pull means, and

(h) means for energizing said heater winding by flow of current therethrough only when the lesser load is connected to the flasher.

2. A snap action flasher for flashing lesser and greater loads at substantially the same rate which comprises:

(a) a first terminal,

(b) a buckling member which is inherently biased toward a first position and held in a second position against said bias by a cold heat-expansible linear pull means secured to said buckling member under tension, said pull means expanding when heated to permit said buckling member to snap toward said first position, and said buckling member being electrically connected to said first terminal,

(c) a pair of movable contacts mounted upon said pull means in spaced apart position with the portion of said pull means bridged between said spaced contacts being less than the total length of said pull means,

(d) second and third terminals,

(e) a stationary contact mounted upon each of said second and third terminals in position for cooperative make-and-break electrical connection with one of said pair of spaced movable contacts, whereby heating of that portion of said pull means bridged between said spaced movable contacts may be substantially eliminated when the greater load is being flashed.

3. A snap action flasher system for flashing lesser and greater loads at substantially the same rate which comprises:

(a) a first terminal,

(b) a buckling member which is inherently biased toward a first position and held in a second position A against said bias by a cold heat-expansible linear pull means secured to said buckling member under tension, said pull means expanding when heated to permit said buckling member to snap toward said first position, and said pull means-buckling member assembly being electrically connected to said first terminal,

(c) a movable contact mounted upon said pull meansbuckling member assembly,

((1) a second terminal,

(e) a stationary contact mounted upon said second terminal in position for cooperative make-and-break electrical connection with said movable contact, said first terminal, pull means-buckling member assembly, movable and stationary contacts and second terminal being arranged in series for current flow through all of said elements when said movable and stationary contacts are closed,

(15) a third terminal,

(-g) a heater winding one end of which is electrically connected to said pull means and the other end of which is electrically connected to said third terminal, said heater winding being positioned in heat conductive relation to said pull means,

(h) a source of potential connected to said second terminal,

(i) lesser and greater loads,

(j) means for connecting either of said lesser and greater loads to said first terminal, and

(k) means for connecting said third terminal across said course when said lesser load is connected to said first terminal and for disconnecting said third terminal from said source when said greater load is connected to said first terminal.

4. A snap action flasher system for flashing lesser and greater loads at substantially the same rate which comprises:

(a) a first terminal, (b) a buckling member which is inherently biased toward a first position and held in a second position against said bias by a cold heat-expansible linear pull means secured to said buckling member under tension, said pull means expanding when heated to permit said buckling member to snap toward said first position, and said buckling member being electrically connected to said first terminal,

(c) a pair of movable contacts mounted upon said pull means in spaced apart position with the portion of said pull means bridged between said spaced contacts being less than the total length of said pull means,

(d) second and third terminals,

(e) a stationary contact mounted upon each of said second and third terminals in position for cooperative make-and-break electrical connection with one of said pair of spaced movable contacts,

(f) a source of potential connected to one of said sec- 0nd and third terminals,

(g) lesser and greater loads,

(h) means for connecting either of said lesser and greater loads to said first terminal, and

(i) means for connecting the other of said second and third terminals to said source when said lesser load is connected to said first terminal and for disconnecting the other of said second and third terminals from said source when said greater load is connected to said first terminal.

References Cited UNITED STATES PATENTS JOHN W. HUCKERT, Primary Examiner.

I. D. CRAIG, Assistant Examiner. 

